Machines such as blast hole drills are large machines used to drill holes for explosives in mining operations. A conventional blast hole drill comprises a frame supported by crawlers for movement over the ground, and a mast supported by the frame for movement between a substantially vertical position and a number of angled or non-vertical positions. A hydraulic gearbox is used to rotate a pipe of the machine to perform a drilling operation. The gearbox is capable of sliding along the mast. A guide structure is used to attach the gearbox to the mast. The guide structure includes wear pads provided thereon for preventing direct steel-to-steel contact between the guide structure and the mast, increasing time between service intervals and allowing smooth sliding of the gearbox.
In known guide structure designs the wear pads are bolted onto the guide structure in such a manner that it may be difficult to adjust the wear pads. The wear pads may need to be removed for replacement purposes or readjusted to maintain required contact with the mast on a regular basis. The current guide structures are designed such that a user's ability to access and adjust the wear pads is limited. Further, the guide structure may offer restricted space for removing the wear pad. Also, in some situations, the gearbox may need to be fully removed and dismantled from the mast in order to access the wear pads. This may be a time consuming, laborious, and inconvenient procedure affecting overall productivity of the system.
United States Published Application Number 2016/0145950 describes a rock drill telescopic arm having a fixed arm which is sleeved on a movable arm; a telescopic oil cylinder; a plurality of adjusting blocks in the fixed arm along a circumferential direction thereof; a plurality of adjusting screw rods for respectively adjusting the position of each of the adjusting blocks on the fixed arm; a wear-resistant sliding block between at least part of the adjusting blocks and the movable arm; and a retainer at an opening end of the fixed arm for preventing the wear-resistant sliding block from moving along a telescoping direction of the movable arm.